PREFACE 



IT is the purpose of this book to present a brief but 

 up-to-date account of our knowledge of the sexual 

 physiology of the vertebrates. During the past generation 

 a whole library has been written around this subject, 

 and therefore in such small space it is impossible to do 

 more than introduce the main facts and theories. For 

 those who would read further, references are made 

 throughout the text to the more important reviews and 

 original papers, and these are listed at the end of the 

 book. Indeed, it is hoped that this introduction to the 

 subject may even stimulate a few of its readers to 

 venture further and to make their own observations in 

 this field. Particularly is it to be hoped that more 

 zoologists will pay attention to the problems of vertebrate 

 reproduction for, while veterinary and medical men are 

 studying the patterns of mammalian reproduction in 

 considerable detail, the richest results will undoubtedly 

 come to those who can take the broader view and 

 think in terms of the evolution of physiological mech- 

 anisms. 



This book was begun in the University of Sheffield 

 and completed in the University of Utrecht. It is a great 

 pleasure to acknowledge the encouragement and friendly 

 criticism received in Sheffield from Professor L. E. S. 

 Eastham and Dr. E. T. B. Francis, and in Utrecht from 

 Professor G. J. van Oordt and his various colleagues. 

 Since many of the fields of research here reviewed have 

 been investigated in Professor van Oordt's department, 

 it is particularly fortunate that opportunity has been 

 found to make a protracted visit to Utrecht. This has 

 been made possible by grants from the Royal Society 

 of London and the University of Sheffield, and also by 

 the extraordinary generosity and hospitality of the Dutch 



